2074 Inorganic Chemistry, VoZ. 11, No. 9,1972
APPLETON,CLARK, AND PUDDEPHATT
of the carbene-like ligands but do not allow a determination of the configuration of the presumably planar ligands. Preliminary X-ray results17indicate that the complex has a trans arrangement of ligands about platinum. (17) J.
H.Enemark, personal communication.
Acknowledgment.-This research was supported by Grants GM-18357 and AM 12182 from the National Institutes of Health. We thank Dr. A. Burke for experimental assistance during the early stages of this work, Professor L. F. Dah1 for a preprint of ref 16, and Professor J. H. Enemark for helpful discussions.
CONTRIBUTION FROM THE DEPARTMENT OF CHEMISTRY, UNIVERSITY O F WESTERN ONTARIO, LOKDON, ONTARIO, CANADA
-
Reactions of 3,3,3 Trifluoropropyne with Methylplatinum (II) Complexes BY T. G. APPLETON, H. C. CLARK,*
AND
R. J. PUDDEPHATT
Received October 26, 1971 3,3,3-TriAuoropropyne, CF&=CH, reacts with complexes of the types cis-Pt(CH&Le and trans-PtCI(CHa)Lz, where L = P(CH3)a(CsH6) (Q), A s ( C H ~ )or ~ ,As(CH&(CeHb), to give varying amounts of polymer and organoplatinum products. Polymerization occurs by an ionic mechanism. Major products from the reaction of PtCl(CH3)Qz with CF3CrCH in benzene are truns-PtCl(-C=CCF3)Qa, truns-PtCl( C(CF3)=CHCl]Q*, truns-Pt(-C~CCFB)2Qz, and P~CIZ(CH~)ZQZ. In alcohols, ROH, PtC1(CHs)Qzreacts with C F a C r C H to give complexes of the type trans-PtCl( C(CF3)=CH(OR)}Q2.
Introduction Continuing our studies1+ on the reactions of unsaturated compounds with methylplatinum (11) complexes, we have investigated the reactions of 3,3,3trifluoropropyne, CFICsCH, with complexes transPtCI(CH3)Lz and cis-Pt(CH&Lz, where L = P(CH&(COHF,), As(CH3)3, or As(CH&(CsH6); Q will be substituted for P(CH&(CaHS). The reactions of this acetylene with a variety of metal complexes have been We have found that CF~CSCH is polymerized by methylplatinum(I1) complexes. Our results suggest that this polymerization does not occur by the mechanism which has been proposed8-'0 for the polymerization of phenylacetylene by complexes of platinum group metals Ph-CTC-H
Dh C/rll
\
M,
H
,c=c
/c
+
etc.
P 'h
Rather, polymerization is anionic, initiated by the electron-rich organoplatinum complex, either directly or via a five-coordinate intermediate, (1) H. C. Clgrk and R. J. Puddephatt, Inovg. Chem., 9 , 2670 (1970). (2) H. C. Clark and R. J. Puddephatt, $bid., 10, 18 (1971). (3) H. C. Clark and R . J. Puddephatt, ibid., 10, 416 (1971). (4) D. A. Harbourne and F. G. A. Stone, J . Chem. Soc. A , 1765 (1968). (5) M. 1. Bruce, D. A. Harbourne, F. Waugh, and F. G. A. Stone, ibid.. 895 (1968). (6) R. S. Dickson and P. J. Fraser, Aust. J . Chem., 23, 2403 (1970). (7) J. T. Mague, E. H . Gause, and Ivf. 0. Nutt, Abstracts, l 6 l s t National Meeting of the American Chemical Society, Los Angeles, Calif., March 28April 2, 1971, No. INOR 133. (8) L. S. Meriwether, M. F. Leto, E. C. Colthup, and G. W. Kennedy, J . Org. Chem., 27, 3930 (1962). (9) A. Furlani, I, Collamati, and G. Sartori, J. OvganometaL Chem., 17, 463 (1969). (10) H. Dietl, H. Reinheimer, J. Moffat, and P. M. Maitlis, J. Amer. Chem. Soc., Sa, 2276 (1970).
Results Characterization of Reaction Products.-When the polymer was obtained, it formed as a white precipitate in the reaction mixture. A typical polymeric product decomposed slowly above 115O, gave infrared bands a t 1610 and 1670 cm-I arising from C=C groupings, and was insoluble or very sparingly soluble in common organic solvents. These properties suggest that the polymer is cross-linked, since linear polyacetylenes are usually highly colored, and soluble in organic solvents," although X-ray powder photographs show an unexpectedly large degree of crystallinity. The filtrate after removal of polymer usually contained a fairly complex mixture of organoplatinum complexes. In some cases the major products could be isolated using column chromatography. Otherwise, the products were identified, or their natures ascertained, from nmr spectra (especially 19Fnmr) of crude of partially separated reaction mixtures. Major products in most reactions contained 3,3,3-trifluoropropynylplatinum groups, Pt-C=CCF3, or substituted vinylplatinum groups of the type Pt
\
/H
CF3/c=c\x
The spectroscopic features of these groups, used to characterize the complexes, are described below. The 3,3,3-trifluoropropynylplatinum cornplexesl2 show a strong infrared absorption in the region 21002150 cm-I corresponding to CGC stretching. Their l9F nmr spectra show sharp peaks in the region 46-48 ppm upfield from CFCI, with coupling (19-35 Hz) to IgGPt( I = l / 2 , 34% abundant). For phosphine complexes, coupling with 31Pnuclei is also observed. The complexes containing vinylplatinum groups, PtC(CF3)=CH(X) (X = OR, Cl), show a moderately (11) W. W. Hausser and R. Kuhn, Z. Phys. Chem., Abt. B. 29, 363 (1935). (12) M . I. Bruce, D. A. Harbourne, F. Waugh, and F. G. A. Stone, J. Chem. SOC. A , 366 (1968).
Inorganic Chemistry, Vol. 11, No. 9, 1972 2075
REACTIONS OF 3,3,3-TRIFLUOROPROPYNE strong peak corresponding to C=C stretching near 1600 em-’. A sharp singlet occurs in the lgFspectrum near 50 ppm upfield from CFC13, with “satellites” from coupling to lg5Pt(120-130 Hz). Comparison of this coupling constant with those in the literature (Table I) indicates that the trifluoromethyl group is TABLEI PLATINUM-FLUORINE COUPLING CONSTANTS IN SOME SUBSTITUTED VINYL-PLATIWUM COMPLEXES (Hz)
C1‘
J+F
Jpt-F
Jpt-F
(gem)
(trans)
(cis)
142.3
5.82
a
5.82
a
Ref
‘PEt3
A
B
13.46
a
C
128.3
The absence of coupling between the CF3 group and the vinylic proton is also consistent with this structure.14 When X is an alkoxy group, typical peaks occur in the nmr spectra. For phosphine complexes, assignment of geometrical isomers with respect to platinum was based on the wellknown mle15J6 that with trans complexes the phosphine methyl groups give 1:2 : 1 triplets from coupling with both 31Pnuclei, while cis complexes give doublets, since each methyl group couples to only one 3lP nucleus. For arsine complexes, probable assignments could be made by comparison with the corresponding phosphine complexes and by taking into account the trans influences of other groups coordinated to the platinum atom. The phosphine methyl region of the spectrum of trans-PtI{-C(CFa)=CH(OCH3) )Qz, like that of the complexes’ trans-PtCl{-C(CF3)=C(CH3) ( C S ) } Qz, shows two overlapping triplets, corresponding to nonequivalent phosphine methyl groups. The complexes trans-PtCl{-C(CS)=CH(X)} Qz (X = C1, OR) show only one triplet (apart from “satellites” from coupling to lg5Pt). Nonequivalence of the phosphine methyl groups implies that the vinyl group occupies the position illustrated below, perpendicular to the plane of the complex,’ with slow rotation about the Pt-C bond. This need not necessarily imply extensive R
6.2
\
D
72.7
E
C”3
b
130 F
H. C. Clark and W. S. Tsang, J. Amer. Chem. SOL,89, 533 (1967). b D. M. Barber, R. D. W. Kemmitt, and G. W . Littlecott, Chem. Commun.,613 (1969). 4
geminal to Pt, No measurable coupling to 31Pwas observed in the phosphine complexes obtained (in which the phosphine ligands were both cis to the vinyl group). The resonance from the vinylic proton occurs new- 5 ppm downfield from TMS. Small couplings (
